Hydraulic pump



Jan. 24, 1967 ZYSTEIN BJQRNDAL HYDRAUL I C PUMP 3 Sheetsheet L 7 FiledMarch 19, 1964 W m m w w w ix z 27,.

w M. 1... mm 6 2 6 6 5 .d 3 Q 43 D! m 2 3 2 3 5 3 INVENTOR: v 0Y5 TE INBJQRNDAL Y. B (WI/meow d- E am 41 J 1967 ZYSTEIN BJQRNYDAL 5Sheets-Sheet 2 FIG. 2

United States Patent M 2 Claims. (cl. 103-426) This invention relates toliquid pumps and particularly to pumps of the kind adapted to be used inhydraulic transmission systems of the hydrostatic type as the pump ormotor thereof.

Particularly in hydraulic transmission systems for winches, it isdesired to have pumps operating at relatively high speeds for deliveringlarge quantities of liquid at relatively high pressures. Heretofore,pumps of the kind having radially extending vanes have been mostcommonly used in such systems, although other kinds of pumps have alsobeen embodied. A ditficulty in such pumps is to provide a satisfactorytightening effect between moving faces without undue wear on such faces.

It is an object of the present invention to provide a pump wherein anexcellent tightening eifect is obtained at moving faces, allowingclearances to be maintained at such faces while avoiding wear as much aspossible.

Another object of the present invention is to provide a pump or motor ofthe stated kind in which stresses on moving parts are relieved as muchas possible, whereby the pump or motor may operate at high pressureswithout any detrimental effect on the pump or motor.

The pump or motor according to the present invention is of the kindcomprising a housing, first and second shafts arranged side by side insaid housing and mounted for rotation in opposite directions, a firstsheave means keyed to said first shaft and carrying a set of protrudingsegment members protruding in axial direction from one side of saidsheave means, a second sheave means keyed to said second shaft andcarrying a set of protruding segment members protruding in axialdirection from one side of said second sheave means, said second sheavemeans being axially spaced from said first sheave means, each set ofsegment members being received within a respective one of two ringchannels ararnged within said housing so as to overlap at a portionthereof, at which portion said sets of segment members are meshing sothat a segment member of the first sheave means will engage into thespace between two successive segment members of the second sheave means,and means for relieving axial pressure created against said sheaves bythe pumping effect at the rotation of said shafts.

In order that the invention can be more clearly understood, it will now,by way of example, he described with reference to the accompanyingdrawings in which:

FIGURE 1 is an axial sectional view of a hydraulic pump or motor meansin a first embodiment of the invention.

FIGURE 2 is a sectional view of the pump as taken along the line 11-11of FIG. 1.

FIGURE 3 is an axial sectional view of a second embodiment.

Whenever referring in this description to a hydraulic pump, it is to beunderstood that the arrangement of the invention may as well be used asa hydraulic motor. As is Well known, the hydraulic motors used in suchhydrostatic systems as are used for instance for cargo winches of a shipare in fact pumps the rotors of which are set into rotation by thecirculating driving liquid, while the liquid in a pump is set intomotion by the movement of the rotor.

For the sake of simplicity the subject matter of the Patented Jar 1.x24,1967 invention will in the course of the description be designated as apump.

The pump according to FIGS. 1 and 2 comprises a housing constituted oftwo parts 10 and 11 secured together by bolts 12. Mounted on rollerbearings 13 in this housing is a first shaft 14 terminating at one endin a stub shaft 15 extending to the outside of the housing for couplingthe pumps to a prime mover, not shown, for instance a diesel engine on aship. The opposite end of the shaft 14 carries a gear wheel 16 in meshwith a second gear wheel 17 keyed to a second shaft 18 mounted on rollerbearings 19 in the housing. The gear wheels 16 and 17 have the samediameters, wherefore the shafts 14 and 18 will rotate with the samerotational speed but in opposite directions.

The first shaft 14 supports a sheave 20 mounted between two thrust ballbearings 21. The second shaft 18 supports a similar sheave 22 mountedbetween two thrust ball bearings 23. Both sheaves are axially spacedfrom each other, whereby two circular chambers 24, 25 are formedtherebetween, said chambers overlapping at a portion 26. An inlet 27 andan outlet 28 are arranged at said intermediate portion 26.

The first sheave 20 carries in the embodiment shown two diametricallyopposed segment members 29, 30 each extending over of the periphery andbeing tightly fitted into the lower chamber 24. The second sheavesimilarly carries two diametrically opposed segment members 31, 32 whichalso extend over 90 of the periphery, said segment members being fittedwith a snug fit into the upper chamber 25. The four segment members 29-32 are arranged so that a segment member on the first sheave will meshbetween 'both segment members of the second sheave at the intermediateportion 26. By the mesh of the gear wheels 16, 17 the segment memberswill, when they meet, be kept at a small distance from each other sothat they are not actually in contact.

On the sides of the sheaves opposing the segment members 29-32 recesses33 are arranged, said recesses communicating with the side carrying thesegment members 29-32 by passages 34. In FIGURE 2 only one such recess33 is shown, but it will be understood that similar recesses are presentat each of the portions of the sheaves where no segment member isarranged on the opposite side of the sheave. In the peripheral directioneach recess extend over somewhat more than 90, as shown in FIG. 2.

The shaft 18 is fully enclosed within the housing by means of a block 35supporting the left hand bearing 19 and a disc 36 (FIG. 1). The righthand end of shaft 18 is covered by the housing part 11. Tightening atthe stub shaft 15 of the first shaft 14 is obtained by means of a blockmember 37 supporting a packing support 38 with associated packing gland39. These members are kept in position by bolts 40.

Discharge fluid from the hydraulic system is supplied to the housingpart 11 enclosing the gear wheels 16, 17 by an opening 41. Bores 41a arearranged to supply lubricating hydraulic fluid to the different ball androller bearings.

When now considering the mode of action of the pump, it will be easy tosee that a pumping action similar to that of a gear pump will beobtained when the sheaves 20, 22 are rotated. However, this pump willnot have the disadvantages inherent in conventional gear pumps, as thehearings will not be subjected to undue stresses, whereas the contactingfaces on the gear wheels 16, 17 will be lubricated by low pressurefluid.

An important feature in the pump is the arrangement of the recesses 33and associated bores 34, whereby axial forces created by the fluid underpressure are substantially relieved. Even when operating at highpressures, there will be no significant decrease in the delivery of thepump and when operating as a hydraulic motor in a hydraulic system, ahigh torque maybe generated by utilising higher pressures. Particularlyby relieving axial forces the pressure in the system will not tend tourge coacting members apart. 7

In the embodiment of FIG. 3 is indicated in a sectional viewcorresponding to FIG. 2'how a third sheave 42 may be arranged withsegment members 43, 44 an inlet 45 and an outlet 46 being arranged tocooperate therewith. Hereby, a double acting pump or motor is obtained,whereby a suitable interconnection of the inlets 27, 45 and the outlets28, 46 for instance by series connection on one hand and connection inparallel on the other hand enables a stepped delivery or consumption tobe obtained.

It should be noted that the use of only two diametrically opposedsegment members is given by example only. It is as well possible to havea number of segment members on each sheave. It is also possible to usesheaves having different diameters provided that the linear length oftheir segment members are equal. Thus, it will be possible to use alarger central sheave than the outer sheaves.

While I have shown only two embodiments of my invention, it will, ofcourse, be understood that I do not wish to be limited thereto sincevarious modifications may be made to the arrangement disclosed, and Iaim by the appended claims to cover any such modifications as fallwithin the true spirit and scope of the invention.

What I claim is:

1. A hydraulic pump comprising, a housing, first and second shaftsarranged side-by-side in said housing and mounted for rotation inopposite directions, a first sheave keyed to said first shaft andcarrying a set of protruding segment members extending in axialdirection from one side of said sheave, a second sheave keyed to thesecond shaft and carrying a set of protruding segment members protrudingin axial direction from one side of said second sheave, said secondsheave being axially spaced from the first sheave, each set of segmentmembers being received within a respective one of two ring channelsarranged within said housing so as to overlap at a portion thereof, atwhich portion said sets of segment members are meshing so that a segmentmember of the first sheave will engage into the space between twosuccessive segment members of the second sheave, means for relievingaxial pressure created against said sheaves by the pumping effect at therotation of the shafts, aid means for relieving the axial pressureconsisting of arcuate recesses arranged along the side face of thesheaves opposite to the face thereof on which the segment members arelocated, each of said recesses extending over a peripheral distancesomewhat greater than the peripheral spacing between successive segmentmembers, the sheaves being provided with bores extending transverselythrough them at points between the segment members and which boresestablish communication, during rotation of the sheaves, between thearcuate recesses and the ring channels.

2. A hydraulic pump according to claim 1, wherein the bores through thetwo sheaves are arranged so that the bores in both of the sheavesestablish communication at times between the respectvie arcuate recessesand the same portion of the ring channels.

References Cited by the Examiner DONLEY J. STOCKING, Primary Examiner.

SAMUEL LEVINE, MARK M. NEWMAN, MARTIN P. SCHWADRON, Examiners.

W. L. FREEH, Assistant Examiner.

1. A HYDRAULIC PUMP COMPRISING, A HOUSING, FIRST AND SECOND SHAFTSARRANGED SIDE-BY-SIDE IN SAID HOUSING AND MOUNTED FOR ROTATION INOPPOSITE DIRECTIONS, A FIRST SHEAVE KEYED TO SAID FIRST SHAFT ANDCARRYING A SET OF PROTRUDING SEGMENT MEMBERS EXTENDING IN AXIALDIRECTION FROM ONE SIDE OF SAID SHEAVE, A SECOND SHEAVE KEYED TO THESECOND SHAFT AND CARRYING A SET OF PROTRUDING SEGMENT MEMBERS PROTRUDINGIN AXIAL DIRECTION FROM ONE SIDE OF SAID SECOND SHEAVE, SAID SECONDSHEAVE BEING AXIALLY SPACED FROM THE FIRST SHEAVE, EACH SET OF SEGMENTMEMBERS BEING RECEIVED WITHIN A RESPECTIVE ONE OF TWO RING CHANNELSARRANGED WITHIN SAID HOUSING SO AS TO OVERLAP AT A PORTION THEREOF, ATWHICH PORTION SAID SETS OF SEGMENT MEMBERS ARE MESHING SO THAT A SEGMENTMEMBER OF THE FIRST SHEAVE WILL ENGAGE INTO THE SPACE BETWEEN TWOSUCCESSIVE SEGMENT MEMBERS OF THE SECOND SHEAVE, MEANS FOR RELIEVINGAXIAL PRESSURE CREATED AGAINST SAID SHEAVES BY THE PUMPING EFFECT AT THEROTATION OF THE SHAFTS, SAID MEANS FOR RELIEVING THE AXIAL PRESSURECONSISTING OF ARCUATE RECESSES ARRANGED ALONG THE SIDE FACE OF THESHEAVES OPPOSITE TO THE FACE THEREOF ON WHICH THE SEGMENT MEMBERS ARELOCATED, EACH OF SAID RECESSES EXTENDING OVER A PERIPHERAL DISTANCESOMEWHAT GREATER THAN THE PERIPHERAL SPACING BETWEEN SUCCESSIVE SEGMENTMEMBERS, THE SHEAVES BEING PROVIDED WITH BORES EXTENDING TRANSVERSELYTHROUGH THEM AT POINTS BETWEEN THE SEGMENT MEMBERS AND WHICH BORESESTABLISH COMMUNICATION, DURING ROTATION OF THE SHEAVES, BETWEEN THEARCUATE RECESSES AND THE RING CHANNELS.